news from BRE
published: 5/4/2011
Difficult demolition wastes study
The CREO house at BRE was finally deconstructed this month and BRE's Resource Efficiency team took the opportunity to learn more about the end-of-life implications of dealing with such a structure.
As part of the full scale build for BRE’s Insite exhibition in the Summer of 2009, construction began of the demonstration building using insulated concrete formwork (ICF) on the Innovation Park at BRE’s main site in Watford.Unlike conventional concrete buildings, where temporary formwork is set up and removed once the concrete is cured, in an ICF building, the formwork is built using large, hollow polystyrene blocks. These are infilled with concrete and reinforcing bar as the construction progresses, with the polystyrene remaining in place as an insulating layer to the completed structure.
The building was left in an incomplete state to allow exhibition visitors to see and understand how an ICF building worked, with a plan to finish the project at a later time. But owing to a number of factors beyond BRE’s control this did not happen, and the unfinished structure has now been removed to make way for further demonstration buildings on the Innovation Park.
The BRE Trust are funding a research project that is seeking to maximise the recovery of building products from innovative systems that are seen as difficult to reuse, recycle or recover at the demolition stage, and BRE’s Resource Efficiency team have been gathering data to support this project. The deconstruction of the ICF building at BRE has provided further useful data for this study.
Ahead of the deconstruction, a pre-demolition audit was performed using BRE’s Smartwaste tool, which predicted that the process to remove and recycle the ICF building would generate about 250m3 of material. The key product by weight would be around 278 tonnes of concrete, and an estimated 131m3 of expanded polystyrene. Other wastes would include the reinforcing bar, small amounts of plasterboard from the rooms that were internally fitted-out, and glass and timber from the window units.
Whilst the concrete and steel are relatively easy to divert from landfill, saving perhaps £15,000 of disposal costs for this project, the polystyrene presents a greater challenge. Transporting the large volumes but small weights of this waste stream would not be cost effective except over short distances to local facilities. However, because the polystyrene waste also contains small amounts of concrete, and because it is no longer in tact as complete blocks showing the recycling codes, it is proving to be difficult to reprocess.
Since a key objective of this project was to have zero waste to landfill, for now the polystyrene has been stockpiled on site while we explore alternative viable solutions. These include heating and compressing the expanded polystyrene back into rigid polystyrene, which can then be used in products such as carpet underlay; or incineration with the heat being recovered to district heating schemes or for electricity generation.
The outcome from the project will be presented as a BRE Trust report later in the year.
For more information, please contact the BRE Smartwaste team by e-mailing smartwaste@bre.co.uk
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